use std::collections::HashMap;

#[derive(Debug,PartialEq)]
pub enum Method{
    Get,
    Post,
    Uninitialized,
}

impl From<&str> for Method{
    fn from(s:&str)->Method{
        match s{
            "GET"=>Method::Get,
            "POST"=>Method::Post,
            _=>Method::Uninitialized,   
        }
    }
}

#[derive(Debug,PartialEq)]
pub enum Version{
    V1_1,
    V2_0,
    Uninitialized,
}

#[derive(Debug,PartialEq)]
pub enum Resource{
    Path(String),
}

impl From<&str> for Version{
    fn from(s:&str)->Version{
        match s{
            "HTTP/1.1"=>Version::V1_1,
            _=>Version::Uninitialized,
        }
    }

} 

#[derive(Debug)]
pub struct HttpRequest{
    pub method: Method,
    pub version:Version,
    pub resource:Resource,
    pub headers:HashMap<String,String>,
    pub msg_body:String,
}

impl From<String> for HttpRequest{
    fn from(req: String) -> Self {
        let mut parsed_method = Method::Uninitialized;
        let mut parsed_version=Version::V1_1;
        let mut parsed_resouce=Resource::Path("".to_string());
        let mut parsed_headers=HashMap::new();
        let mut parsed_msg_body="";

        for line in req.lines(){
            if line.contains("HTTP"){
                let (method,resource,version)=process_req_line(line);
                parsed_method=method;
                parsed_version=version;
                parsed_resouce=resource;
            }else if line.contains(":"){
                let (key,value)=process_header_line(line);
                parsed_headers.insert(key,value);
            }else if line.len()==0{

            }else{
                parsed_msg_body=line;
            }
        }
        HttpRequest{
            method:parsed_method,
            version:parsed_version,
            resource:parsed_resouce,
            headers:parsed_headers,
            msg_body:parsed_msg_body.to_string(),
        }
    }
}

fn process_req_line(s:&str)->(Method,Resource,Version){
    let mut words=s.split_whitespace();
    let method=words.next().unwrap();
    let resource=words.next().unwrap();
    let version=words.next().unwrap();
    (
        method.into(),
        Resource::Path(resource.to_string()),
        version.into(),
    )
}

fn process_header_line(s:&str)->(String,String){
    let mut header_items=s.split(":");
    let mut key=String::from("");
    let mut value=String::from("");
    if let Some(k)=header_items.next(){
        key=k.to_string();
    }
    if let Some(v)=header_items.next(){
        value=v.to_string();
    }
    (key,value)
}

//test
#[cfg(test)]
mod tests{
    use super::*;

    #[test]
    fn test_method_into(){
        let m:Method="GET".into();
        assert_eq!(m,Method::Get);
    }

    #[test]
    fn test_version_into(){
        let v:Version="HTTP/1.1".into();
        assert_eq!(v,Version::V1_1);
    }

    #[test]
    fn test_read_http(){
        let s:String=String::from("GET /greeting HTTP/1.1\r\nHost: localhost:3000\r\nUser-Agent: curl/7.71.1\r\nAccept: */*\r\n\r\n");
        let mut headers_expected=HashMap::new();
        headers_expected.insert("Host".into()," localhost".into());
        headers_expected.insert("Accept".into()," */*".into());
        headers_expected.insert("User-Agent".into(), " curl/7.71.1".into());
        let req: HttpRequest=s.into();

        assert_eq!(Method::Get,req.method);
        assert_eq!(Version::V1_1,req.version);
        assert_eq!(Resource::Path("/greeting".to_string()),req.resource);
        assert_eq!(headers_expected,req.headers);
    }
}